(a) Field of the Invention
The present invention relates to an electrophotographic reproduction process which renders it possible to eliminate the residual potential arising from repeated use of a layered photoconductor.
(b) Description of the Prior Art
In electrophotography, there is known the art of producing copied images by repeating the respective steps of charging a layered photoconductor for electrophotography obtained by providing a layer capable of generating electric charge when light is applied thereto (hereinafter called "carrier generation layer") and a layer capable of transporting the thus generated electric charge (hereinafter called "carrier transport layer"), in that order, on a light-transmissible electroconductive support (which element may be further provided with a barrier layer formed on said electroconductive support), effecting image-wise exposure by way of one side of the layered photoconductor and developing subsequent thereto, followed by transfer of the developed image if necessary. In this case, the surface of the layered photoconductor comes to have a potential due to the charging, and the potential of the exposed area (to wit, the non-image area) must be eliminated by the succeeding image-wise exposure. According to this art, however, there still remains a relatively high potential in the exposed area after the exposure, and this residual potential causes conspicuous stains on the resulting images and also constitutes a factor which disturbs the reproduction of continuous gradation.
Meanwhile, in the case where general single layer-type photosensitive elements, such as selenium-type photosensitive element, are employed as a countermeasure for preventing the occurrence of stains on the ground due to residual potential, it is usual to perform the development by applying a developing bias voltage of about 200 V to the photosensitive element. However, application of the same operation to the foregoing laminate-type layered photoconductors has proved to be insufficient for the purpose of eliminating the occurrence of stains on the ground. It is conceivable to raise said bias voltage to a desired value to cover this defect, but from the viewpoint of safety, there is a limit to the applicable voltage and, accordingly, this measure is very difficult to put to practical use.